package org.apache.lucene.demo;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermEnum;
import java.io.File;
import java.util.Date;
import java.util.Arrays;

/** Indexer for HTML files. */
public class IndexHTML {
    private IndexHTML() {
    }

    private static boolean deleting = false; // true during deletion pass
    private static IndexReader reader; // existing index
    private static IndexWriter writer; // new index being built
    private static TermEnum uidIter; // document id iterator

    /** Indexer for HTML files.*/
    public static void main(String[] argv) {
        try {
            String index = "index";
            boolean create = false;
            File root = null;

            String usage = "IndexHTML [-create] [-index <index>] <root_directory>";

            if (argv.length == 0) {
                System.err.println("Usage: " + usage);
                return;
            }

            for (int i = 0; i < argv.length; i++) {
                if (argv[i].equals("-index")) { // parse -index option
                    index = argv[++i];
                } else if (argv[i].equals("-create")) { // parse -create option
                    create = true;
                } else if (i != argv.length - 1) {
                    System.err.println("Usage: " + usage);
                    return;
                } else
                    root = new File(argv[i]);
            }

            Date start = new Date();

            if (!create) { // delete stale docs
                deleting = true;
                indexDocs(root, index, create);
            }
            writer = new IndexWriter(index, new StandardAnalyzer(), create);
            writer.setMaxFieldLength(1000000);
            indexDocs(root, index, create); // add new docs

            System.out.println("Optimizing index...");
            writer.optimize();
            writer.close();

            Date end = new Date();

            System.out.print(end.getTime() - start.getTime());
            System.out.println(" total milliseconds");

        } catch (Exception e) {
            System.out.println(" caught a " + e.getClass() + "\n with message: " + e.getMessage());
        }
    }

    /* Walk directory hierarchy in uid order, while keeping uid iterator from
    /* existing index in sync.  Mismatches indicate one of: (a) old documents to
    /* be deleted; (b) unchanged documents, to be left alone; or (c) new
    /* documents, to be indexed.
     */

    private static void indexDocs(File file, String index, boolean create) throws Exception {
        if (!create) { // incrementally update

            reader = IndexReader.open(index); // open existing index
            uidIter = reader.terms(new Term("uid", "")); // init uid iterator

            indexDocs(file);

            if (deleting) { // delete rest of stale docs
                while (uidIter.term() != null && uidIter.term().field() == "uid") {
                    System.out.println("deleting " + HTMLDocument.uid2url(uidIter.term().text()));
                    reader.delete(uidIter.term());
                    uidIter.next();
                }
                deleting = false;
            }

            uidIter.close(); // close uid iterator
            reader.close(); // close existing index

        } else // don't have exisiting
            indexDocs(file);
    }

    private static void indexDocs(File file) throws Exception {
        if (file.isDirectory()) { // if a directory
            String[] files = file.list(); // list its files
            Arrays.sort(files); // sort the files
            for (int i = 0; i < files.length; i++) // recursively index them
                indexDocs(new File(file, files[i]));

        } else if (file.getPath().endsWith(".html") || // index .html files
                        file.getPath().endsWith(".htm") || // index .htm files
                        file.getPath().endsWith(".txt")) { // index .txt files

            if (uidIter != null) {
                String uid = HTMLDocument.uid(file); // construct uid for doc

                while (uidIter.term() != null && uidIter.term().field() == "uid" && uidIter.term().text().compareTo(uid) < 0) {
                    if (deleting) { // delete stale docs
                        System.out.println("deleting " + HTMLDocument.uid2url(uidIter.term().text()));
                        reader.delete(uidIter.term());
                    }
                    uidIter.next();
                }
                if (uidIter.term() != null && uidIter.term().field() == "uid" && uidIter.term().text().compareTo(uid) == 0) {
                    uidIter.next(); // keep matching docs
                } else if (!deleting) { // add new docs
                    Document doc = HTMLDocument.Document(file);
                    System.out.println("adding " + doc.get("path"));
                    writer.addDocument(doc);
                }
            } else { // creating a new index
                Document doc = HTMLDocument.Document(file);
                System.out.println("adding " + doc.get("path"));
                writer.addDocument(doc); // add docs unconditionally
            }
        }
    }
}
